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时间:2018-07-27
《科技英语 4低通滤波器 原文与翻译》由会员上传分享,免费在线阅读,更多相关内容在教育资源-天天文库。
1、WordsandExpressions9integratorn.积分器amplituden.幅值slopen斜率denominatorn.分母impedancen阻抗inductorn.电感capacitorn电容cascaden.串联passbandn通带ringingn.振铃dampingn.阻尼,衰减conjugateadj.共轭的stagev.成为9low-passfilters低通滤波器buildingblock模块linearramp线性斜坡log/logcoordinates对数/对数坐标Bodeplot伯德图transferfunction传递
2、函数complex-frequencyvariable复变量complexfrequencyplane复平面realcomponent实部frequencyresponse频率响应complexfunction复变函数Laplacetransform拉普拉斯变换realpart实部imaginarypart虚部angularfrequency角频率frequencyresponse频率响应transientresponse瞬态响应decaying-exponentialresponse衰减指数响应stepfunctioninput阶跃(函数)输入timecon
3、stant时间常数first-orderfilters一阶滤波器second-orderlow-passfilters二阶低通滤波器passivecircuit无源电路activecircuit有源电路characteristicfrequency特征频率qualityfactorn.品质因子,品质因数circularpath圆弧路径complexconjugatepairs共轭复数对switched-capacitor开关电容9negative-realhalfofthecomplexplane复平面负半平面9Unit4Low-passFiltersFirs
4、t-OrderFiltersAnintegrator(Figure2.la)isthesimplestfiltermathematically,anditformsthebuildingblockformostmodernintegratedfilters.Considerwhatweknowintuitivelyaboutanintegrator.IfyouapplyaDCsignalattheinput(i.e.,zerofrequency),theoutputwilldescribealinearrampthatgrowsinamplitudeuntil
5、limitedbythepowersupplies.Ignoringthatlimitation,theresponseofanintegratoratzerofrequencyisinfinite,whichmeansthatithasapoleatzerofrequency.(Apoleexistsatanyfrequencyforwhichthetransferfunction'svaluebecomesinfinite.)(为什么为极点,为什么低通?)Figure2.laAsimpleRCintegratorWealsoknowthattheinteg
6、rator'sgaindiminisheswithincreasingfrequencyandthatathighfrequenciestheoutputvoltagebecomesvirtuallyzero.Gainisinverselyproportionaltofrequency,soithasaslopeof-1whenplottedonlog/logcoordinates(i.e.,-20dB/decadeonaBodeplot,Figure2.1b).Figure2.1bABodeplotofasimpleintegratorYoucaneasil
7、yderivethetransferfunctionasWheresisthecomplex-frequencyvariableandis1/RC.Ifwethinkofsasfrequency,thisformulaconfirmstheintuitivefeelingthatgainisinverselyproportionaltofrequency.9Thenextmostcomplexfilteristhesimplelow-passRCtype(Figure2.2a).Itscharacteristic(transferfunction)isWhen
8、,thefunctionreduces
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